Lifting of liquid from well tubing



y 1962 J. w. HODGES 3,031,976

7 LIFTING OF LIQUID FROM WELL TUBING Filed Aug. 21, 1958 2 Sheets-Sheet 1 INVENTOR. JAMES W. HODGES tux-20L;hs M

A TORNEY y 1962 .I. w. HODGES 3,031,976

LIFTING OF LIQUID FROM WELL TUBING Filed Aug. 21, 1958 2 Sheets-Sheet 2 Fig. 2

INVENTOR. JAMES W. HODGES A TORNEY Patented May 1, 19%2 3,631,976 LHTING F LIQUID FRGM WELL TUBING James W. Hodges, Beaumont, Tern, assignor to Sun Oil Company, Philadelphia, Pa, a corporation of New Jersey Filed Aug. 21, 1958, Ser. No. 756,413 4 Claims. (61. 103--229) This invention relates to means for lifting liquid from well tubing. The invention more particularly is directed to a device for use within well tubing which will operate when the hydrostatic head of liquid within the tubing reaches a predetermined value, to thereby admit a surge of lifting gas to the tubing.

One of the problems encountered in producing oil or gas wells results from accumulation of salt water in the well tubing until suflicient hydrostatic head has been built up to stop flow from the formation. In such cases various means have been used to reduce the water level so that the well will flow again. The present invention provides improved means for automatically gas lifting liquid from the well tubing whenever the hydrostatic head therein reaches a predetermined value.

In accordance with the invention a control device, which is positioned in the well tubing ata suitable depth, operates to admit a slug of gas to the tubing when the hydrostatic head increases above a predetermined value. The gas may be derived from the formation being produced, either as free gas or as solution gas which is released from liquid phase due to a drop in pressure as the oil stream passes through the device; or it may be gas introduced to the device from the annulus between the tubing and well casing. As the hydrostatic head decreases, the velocity of the gas passing through the device increases until a rate is reached such as to cause the device automatically to shut oh the gas flow. The well is then allowed to flow in the normal manner until such time as the hydrostatic head increases sufflciently to cause the control device to function again and effect lifting of liquid from the tubing. The device has the additional advantageous feature of including means for preventing water from the tubing from flowing back to and standing against the formation whenever the well is shut in for a time.

The invention is morespecifically described with reference to the accompanying drawings in which:

'FIG. 1 is a cross-sectional elevational view of a portion of a cased well showing one embodiment of the control device positioned in the tubing for operation by means of gas derived from the producing formation.

FIG. 2 is a cross-sectional elevational view of a portion of a cased well showing another form of the control device which is operated by means of gas derived from the casing annulus.

FIG. 3 is a cross-sectional view of the device shown in FIG. 2 taken on the line 33.

Referring to FIG. 1, numeral it? illustrates a well casing which passes through a production formation and contains perforations 11 for fluid flow therefrom. Well tubing 9) contains a conventional landing nipple 12 into which the control device is lowered on a wire line and fixed in place by conventional latching means shown generally at 13. The device comprises a housing 14 which projects from the bottom of the tubing as shown at 15. Longitudinal openings 16 in the bottom of the housing, which openings contain screens 17, provide for admission of fluid from the formation into the device. The fluid enters a chamber 18 in which is positioned a bellshaped resilient check valve member 19 that is longitudinally slidable in the chamber. The check valve member 19 should be constructed of a tough elastomeric material, such as the material sold under the mark Neoprene, which is unaffected by well fluids and which has sufficient flexibility for movement of its outer edge against the wall of the housing which serves as a valve seat. A spring 29 urges the check valve member upwardly so that its outer edge is normally above ports 21 in the housing wall. This prevents any downflow of fluid when the device is locked in position in the tubing. However, spring 2i? is sufficiently compressible by fluid pressure when the device is raised through the tubing so that member 19 will be forced downwardly to where its outer edge is beneath ports 21. This permits fluid to pass through the device and outwardly through ports 21 as the device is being raised, thereby avoiding a liquid lock condition.

The housing 14- has a transverse baflle 22. which contains a choke port 23 that can be provided with a choke 24 having a throat suitably sized for normally controlling the rate of flow from the formation. A flow channel leads from chamber is through ports 25 and annular passage 26 to choke port 23, and formation fluid passes through this channel during normal production of the well. O-rings 27 between the housing 14 and tubing 12 prevent by-passing of fluid around the device.

Transverse baffle 22 contains a central port 30 which has a valve seat 31 at its lower end. A ball check valve member 32 has a guide arm 33 extending upwardly through port 30 and terminating at a baffle 34 having flow ports 35 therein in alignment with'the annulus formed in flow port 3t Ports 35' facilitate upward gas flow from such annulus when the valve is in open position with baflie 34 adjacent the mouth of flow port 30.

The housing contains a bellows 28 which opens into chamber 18 and hence is subjected to the pressure of the fluid flowing through such chamber. Bellows 28 is connected to an opposing bellows 29 which contains air or other gas under a predetermined pressure. An arm 36 extends from the lower end of bellows 29 up to ball check member 32 and normally maintains the valve closed so that all of the fluid flow normally passes through choke 24. However, when the hydrostatic head of fluid in the tubing above the valve reaches a predetermined value, the hydrostatic pressure at the upper end of the valve overcomes the differential upward pressure from the bellows arrangement and causes the valve to open. Thi permits a surge of fluid to pass from the annular channel 26 through ports 3'7 in the housing wall and through the check valve port 30. The fluid includes any free gas originally withdrawn from the formation and solutioin gas which is released due to pressure drop of the fluid in passing through the device. Such gas, at the increased flow rate resulting when the valve opens, efiects a lifting action on the liquid in the tubing and causes it to flow from the well. As the hydrostatic head decreases, the rate of fluid flow through the check valve port 30 increases and the force of impingement against baflle 34 correspondingly increases. When the hydrostatic head in the tubing has been decreased sufficiently, the force of impingement will have increased to a point where it lifts the ball check 32 to its seating position, thus stopping the fluid surge. Operation then will return to normal with all fluid flowing through choke 24.

Before the above-described device is placed in the well, it is necessary to pressurize bellows 29 to a predetermined value which will allow the ball check valve to open when the water column in the tubing has reached the maximum permissible height. Such pressure can be calculated openers from the following equation which expresses the balance of forces involved for operating the valve:

P =the flowing bottom hole pressure, A =cross-sectional area of bellows 28,

P =charged pressure of bellows 29, A =cross-sectional area of bellows 29,

W=maximum permissible height of water in. tubing, G pressure gradient of water,

D=dcpth of ball check valve,

G =flowing gradient of fluid above water,

P isurface tubing pressure, and

A =cross-sectional area of flow port 3%.

Accordingly, gas pressure is applied to bellows 2% to correspond to the value of P determined by the foregoing equation and the device is then positioned in the well tubing as shown in FIG. 1. The ball check valve will remain closed until water accumulates in the tubing to the height W. Then the valve will open and admit a surge of gas which progressively increases in rate as the water is lifted from the tubing. When the rate becomes sufliciently high, the force of fluid against the lower side of baflle 34 will lift the valve member 32 and cause it to seat, thus stopping the gas surge.

The resilient check valve 19 in the lower part of the device has an important function when the well is shut in for a time, since it prevents water which has accumulated in the tubing from flowing back to the formation. This ensures against damage of the formation which might occur if a body of water were permitted to stand against it during the shut-in period. The arrangement as shown in FIG. 1, whereby the resilient check valve slides downwardly below ports 21 in opposition to spring 2t] when the device is raised on a wire line, is important in preventing a liquid lock condition.

Referring now to FIGS. 2-3, an arrangement is shown whereby gas from the annulus between casing ll and tubing as is utilized for periodic lifting of accumulated water from the tubing. A packer 42 is positioned in the annulus, and the control device is seated in the tubing adjacent ports therein shown as 43. Annular packing rings 44 are provided between tubing 41 and housing 4-5 above and below ports 43 to direct gas from the annulus through crossover ports 46 in the housing. The gas either may be gas admitted to the casing at the well head or, if a gas sand is available above the packer, may be gas obtained from such formation.

.Fluid from a lower formation flows through casing perforations 4'7 and into the device through screened ports 48. The device has a chamber 49, resilient check valve member Stl, spring 51, ports 52, bellows 53 open to chamber 49, opposed bellows 1- containing gas at a predetermined pressure, an arm 58 extending upwardly from the lower end of bellows 54, and a ball type check valve 55 with baflle 56 at the upper end of its guide arm 57, all as described in connection with FIG. 1. In this case two chokes 59 are provided in transverse baflle 60 for controlling the normal flow of formation fluid. From chamber 49 radial ports 61 connecting with longitudinal channels 62 provide for fluid HOW to the chokes 59.

The device shown in FIG. 2 operates in similar manner to that described in connection with FIG. 1. When sulficient hydrostatic head has built up in the tubing, the ball check valve opens and a surge of gas derived from the casing annulus passes into the tubing and lifts liquid out of the well. When the velocity of the gas becomes sufliciently high, the valve automatically closes and normal flow from the formation is resumed.

It should be noted that the arrangement shown in FIG. 2 can be utilized for intermittently gas lifting an oil well which has sufficient pressure to flow only part way up the tubing. Bellows 54 can be pressurized to a predetermined value such that the ball check valve will open whenever the oil column approaches the maximum height to which it can flow. This will admit a surge of gas and lift the oil from the tubing.

1 claim:

1. A device for automatic lifting of liquid from well tubing when the hydrostatic head therein reaches a predetermined value, which comprises a housing adapted to be positioned within the well tubing, said housing having a side port; a transverse baffle in the housing having therein a choke port and also a flow port; means including said side port forming a first flow channel to said flow port, means forming a second flow channel from the base of the housing to said choke port, resilient check valve means in said second channel for preventing backflow therein when the device is in place in the well tubing, a valve seat at the lower side of said flow port, a valve member cooperating with said seat and having a guide arm extending through said flow port; a baffle on the guide arm in the path of fluid flow above the flow port for urging the valve member closed whenever the fluid flow through said flow port becomes sufiiciently high, a first bellows open to fluid pressure in said second channel, a second bellows arranged for gas pressurization at a predetermined pressure, the first and the second bellows being mechanically coupled together in opposed relation, and means coupling said second bellows to said valve member for maintaining the latter seated until the hydrostatic head of liquid in the well tubing reaches the predetermined value.

2. A device according to claim 1, in which said housing has a port beneath said check valve means, said lastmentioned port communicating at one end with said secand channel and at its other end with the outside of the device, said check valve means being slidable in said second channel; and in which said housing contains a spring which normally urges the check valve means above said last-mentioned port when the device is in place in the tubing but which is compressible by fluid pressure as the device is raised in the tubing to permit the check valve means to slide below said last-mentioned port and allow fluid to pass out of the tubing by way of said lastmentioned port, thereby avoiding a liquid lock condition.

3. A well assembly for automatic lifting of liquid from well tubing when the hydrostatic head therein reaches a predetermined value, which comprises a casing perfo rated for fluid flow from a formation, a well tubing in the casing, a packer sealing the annulus between the tubing and casing, means for admitting gas under pressure to the annulus, and a control device positioned in the tubing above the packer adjacent a tubing port; said control device comprising a housing having a side port for fluid communication with said tubing port; packing means between the housing and tubing above and below said ports, a transverse bafile in the housing having therein a choke port and also a flow port, said flow port communicating with said housing port; means forming a flow channel from the base of the housing to said choke port, resilient check valve means in said channel for preventing baclrfiow therein when the device is in. place in the well tubing, a valve seat at the lower side of said flow port, a valve member cooperating with said seat and hav ing a guide arm extending through said flow port; a baflle on the guide arm in the path of fluid flow above the flow port for urging the valve member closed whenever the fluid flow through said flow port becomes sufficiently high, a first bellows open to fluid pressure in said channel, a second bellows arranged for gas pressurization at a predetermined pressure, the first and the second bellows being mechanically coupled together in opposed relation, and means coupling said second bellows to said valve member for maintaining the latter seated until the hydrostatic head of liquid in the well tubing reaches the predetermined value.

4. A well assembly according to claim 3, in which said housing has a port beneath said check valve means, said last-mentioned port communicating at one end with said channel and at its other end with the outside of the device, said check valve means being slidable in such channel; and in which said housing contains a spring which normally urges the check valve means above said last-mentioned port When the device is in place in the tubing but which is compressible by fluid pressure as the device is raised in the tubing to permit the check valve means to slide below said last-mentioned port and allow fluid to pass out of the tubing by Way of said last-mentioned port, thereby avoiding a liquid lock condition.

References Cited in the file of this patent UNITED STATES PATENTS Grisharn Mar. 25, Peake Aug. 19, Barnes Jan. 12, OLeary Sept. 7, Otis May 9, Staggs May 20, Kagay June 10, Vincent Dec. 23, 

